Here's a list of some terms and abbreviations that are used in DCUO:
ADD/ADDS - additional enemy (usually spawned during boss battles)
AoE - area of effect
AGGRO - aggravate
DOT - damage over time
DPS - damage per second
GLF - group look for
HOT - heal over time
KITE - to remain out of harms way (usually while doing little to no damage)
LFG - looking for group
LFM - looking for more
PvE - player vs environment (computer)
PvP - player vs player
Feel free to add to the list and correct any mistakes that you see.